VALUE OF ROUTINE DIAGNOSTIC-CRITERIA OF BULLOUS PEMPHIGOID

Background and design The clinical, histologic, and direct (DIF) and i ndirect (IIF) immunofluorescence findings are used in a critical, alth ough arbitrary, manner in the routine diagnostic process of bullous pe mphigoid (BP). Our purpose was to estimate their relative value. In th e present retrospective study, a follow-up of at least 18 months was u sed as a prerequisite for the final diagnosis of BP (63 patients) and controls (n = 159). Results The clinical, histologic, DIF, and IIF dia gnostic criteria of BP were found to vary independently of each other. Positive DIF was the most sensitive (90.5%) typical for BP histology and positive IIF were the most specific (99%). Immunopathologic tests were the most valuable, especially in the atypical varieties of BP. Ne arly 25% of patients in this group would have been misdiagnosed if IF tests had not been performed. Atypical cases (40%) seemed to represent a clinical continuum over the whole spectrum of the disease. Patients with exclusively immunoglobulin G (IgG) and C3 basal membrane zone (B MZ) deposits were significantly more often seropositive than the rest of the DIF-positive cases; however, the class of BMZ immunoreactants v aried according to the site of biopsy. C3 was almost invariably deposi ted at the BMZ of DIF-positive patients. When Igs were also present, t hey were only exceptionally (5% of cases) of greater fluorescence inte nsity than C3. Conclusions The combination of clinical data plus one p ositive immunopathologic test provide the best combination of sensitiv ity and specificity (98%), and seem to be most appropriate in defining patient populations for study purposes. The relationship between the classes of immunoreactants should be better evaluated with reference t o the site of skin biopsy. It may be suggested, however, that the like lihood of BP existence is very low when in vivo C3 is absent or of low er intensity of fluorescence than the concomitant Ig(s).